A meme circulating on Twitter recently suggests magenta is not color. We beg …

There is a nasty rumor making its way around the interconnected series of tubes we call the Internet. The rumor was sparked by an article on The Neurostimulation Technology Portal by Liz Elliott entitled "Magenta Ain't A Colour," which has since had people exclaiming, "Fact: Magenta isn't a color," or, "Magenta is a lie." The truth is a little more complicated than that, but I assure you that magenta is not a lie—or at least not any more a lie than any other color.

See, what we call the "visible spectrum" is really a very narrow band in a much larger spectrum of electromagnetic radiation. It is visible because our eyes have cells called "cones" in the retina that are sensitive to these wavelengths—in the range of about 400–700nm—to varying degrees. Some of the cones are sensitive to longer wavelengths, some to medium wavelengths, and others to shorter wavelengths. These wavelengths correspond to (roughly) what we call red, green, and blue light, and form the basis of the RGB color model used by digital images, TVs, flat panels, and more.

This chart shows the range of EM radiation, and the narrow band we call visible light within it.

As visible light enters the eye and strikes the cone cells, the cells send electrical signals along the optic nerve to the brain. This is how our body "senses" light. Our brain interprets those three separate sensations to produce the perception that we call "color."

So back to this rumor that magenta somehow isn't a color. Elliott's thesis centers on the argument that magenta appears nowhere on the spectrum of visible light, so it therefore isn't a "real" color. If you look at a standard CIE chromaticity diagram, which maps wavelengths of light according to human perception, you'll note that every point along the curve corresponds to a single wavelength of light. Magenta, as it were, lies along what's commonly called the "pink-purple line" that runs across the bottom. All colors along this line do not exist as single wavelengths. But, all points inside the "color bag" above that line do not exist as single wavelengths, either.

The truth is, no color actually exists outside of our brain's perception of it. Everything we call a color—and there are a lot more than what comes in your box of Crayolas—only exists in our heads. We define color in terms of how our brains process the stimuli produced by a mix of wavelengths in the range of 400–700nm hitting specialized cells in our eyes—"one, or any mixture, of the constituents into which light can be separated in a spectrum or rainbow," says the OED. Elliot's article might be better titled, "Magenta is not a single wavelength of electromagnetic radiation in the 'visible' spectrum, but our brain perceives it anyway."

So despite what you read on Twitter, Virginia, there is a magenta. And it's all in our heads.

I think it's important to nip this kind of non-scientific "magenta is not a color" stuff in the bud. There's already enough mumbo-jumbo clogging up the net, I'm glad Ars is on the side of good science.

Slow news day? Maybe. In any case I think this is a wonderful, succinct article that dispenses with some terrible non-science. I have historically come to Ars for the well written in-depth technical overviews of topics such as processor microarchitecture but I love articles like this just the same.

Actually, funny you should mention it. I recently had a chat with a relative who was a physics teacher about why the violet end of a spectrum appears reddish-blue (more magenta than "pure" blue). It suggests that either the standard primary colours are wrong ("blue" is actually "greenish violet" and the purity of the colour is psychological) or - my suggestion - that the shorter blue wavelength have harmonics that trigger the red cones (although the diagrams I've seen for cone sensitivity by wavelength don't reflect this).

While it's a slow news day and this is an educated crowd, can anyone give me a more definitive explanation?

"discrete wavelength is necessary for something to exist in nature apart from human interpretation" - this can't be right, it's like saying table salt doesn't exist because it's really just sodium and chlorine ions, salt only exists in our heads.

"Can magenta exist in nature?" - since we have defined magenta as a certain mixture of red and blue frequencies, yes. That mixture of red and blue exists in nature.

It may also be worth noting that while our cones roughly correspond to RGB, by the time that information reaches anything that could be called higher-level processing it's been cast more as YCbCr signals (i.e. black-white, blue-yellow, red-green; or a luma and two chroma signals) and this also has an effect on colour perception.

(There are many probable reasons why our visual cortex works like this, not least that we probably evolved from creatures with monochromatic vision.)

Originally posted by Zetetic Apparatchik:It may also be worth noting that while our cones roughly correspond to RGB, by the time that information reaches anything that could be called higher-level processing it's been cast more as YCbCr signals (i.e. black-white, blue-yellow, red-green; or a luma and two chroma signals) and this also has an effect on colour perception.

(There are many probable reasons why our visual cortex works like this, not least that we probably evolved from creatures with monochromatic vision.)

Interesting. Never thought about it that way. Is this where color-blindness comes in? Someone's brain is screwed up and not properly interpreting the chroma channels, but still getting the luminance right?

This is a perfect example of a sensationalized story that the internets have become perfect at spreading to the unwashed masses.

Somewhere, somehow there is going to be someone that never actually read the original article, nor ARS's follow-up article, and yet they will spread the misinformation that "Magenta is not a color" and claim it as truth.

Let me specify the red I referred to earlier as the wavelength of light which is measured from the H-alpha, which is 656.281 nanometers.

quote:

"discrete wavelength is necessary for something to exist in nature apart from human interpretation" - this can't be right, it's like saying table salt doesn't exist because it's really just sodium and chlorine ions, salt only exists in our heads.

The idea of salt was invented by humans to classify physical phenomena: physical phenomena which existed long before humans ever existed. Salt existed in nature both before human interpretation and after human interpretation.

quote:

"Can magenta exist in nature?" - since we have defined magenta as a certain mixture of red and blue frequencies, yes. That mixture of red and blue exists in nature.

Magenta is a non-spectral color. Does a magenta-colored flower produce a magenta color because it produces light which is at a discrete wavelength or because the flower has pigments, which when combined with waves of light which reach the retina, give humans the perception of magenta?

Originally posted by Hazdaz:This is a perfect example of a sensationalized story that the internets have become perfect at spreading to the unwashed masses.

Somewhere, somehow there is going to be someone that never actually read the original article, nor ARS's follow-up article, and yet they will spread the misinformation that "Magenta is not a color" and claim it as truth.

Can you say that it is "misinformation" so definitively when the question posed about whether something exists because of human perception or because of physical reality apart from human perception necessitates metaphysical philosophical discussion?

Originally posted by Zetetic Apparatchik:It may also be worth noting that while our cones roughly correspond to RGB, by the time that information reaches anything that could be called higher-level processing it's been cast more as YCbCr signals (i.e. black-white, blue-yellow, red-green; or a luma and two chroma signals) and this also has an effect on colour perception.

Given how much time I spend at work ensuring that RGB<->YCbCr conversion doesn't run out of range (and at home, complaining that colour management is broken), it probably should have occurred to me that the human visual system would have rounding/cross-talk errors. Typical - software bug. Thanks.

quote:

(There are many probable reasons why our visual cortex works like this, not least that we probably evolved from creatures with monochromatic vision.)

I guess I should be thankful we don't see in NTSC...

When I'm resurrected, I want to come back as a mantis shrimp. "I want to see gamma rays! I want to hear X-rays! And feel the wind of a supernova flowing over me!"

Originally posted by Vipre77:Interesting. Never thought about it that way. Is this where color-blindness comes in? Someone's brain is screwed up and not properly interpreting the chroma channels, but still getting the luminance right?

No, colour-blindness is (at least usually) a difference at the cone cell level. You get tetrachromats through the same mechanism.

Originally posted by Peter Zavislak:If humans did not exist, would magenta exist? Is human perception necessary for something to exist?Does existence precede essence, or does essence precede existence?

You're conflating the magenta defintion, which we base on our limited perception of a small fraction of the spectrum, with the continuously variable electromagnetic waves that exist in nature. I mean, IR, UV, microwaves, x-rays etc all exist just fine without direct human perception; we had no idea those existed until we built the right tools. And the words themselves are just semi-arbitrary labels for big ranges of wavelengths. You're free to say either "extra-long microwave" or "extra-short radio" to refer to the exact same borderline wave; the verbal distinction doesn't actually exist in nature.

Somehow our brains evolved such that, rather than being confused by a superposition of red and blue waves, we perceive all the permutations as shades of violets and magentas. But those superpositions exist regardless of what we call it.

quote:

Magenta is a non-spectral color. Does a magenta-colored flower produce a magenta color because it produces light which is at a discrete wavelength or because the flower has pigments, which when combined with waves of light which reach the retina, give humans the perception of magenta?

The latter. Unless there are bioluminescent flowers I'm not aware of, flowers do not show an emission spectrum.

"discrete wavelength is necessary for something to exist in nature apart from human interpretation" - this can't be right, it's like saying table salt doesn't exist because it's really just sodium and chlorine ions, salt only exists in our heads.

The idea of saltmagenta was invented by humans to classify physical phenomena: physical phenomena which existed long before humans ever existed. Saltmagenta existed in nature both before human interpretation and after human interpretation.

"discrete wavelength is necessary for something to exist in nature apart from human interpretation" - this can't be right, it's like saying table salt doesn't exist because it's really just sodium and chlorine ions, salt only exists in our heads.

The idea of saltmagenta was invented by humans to classify physical phenomena: physical phenomena which existed long before humans ever existed. Saltmagenta existed in nature both before human interpretation and after human interpretation.

Your supposition that magenta and salt are both equivocal physical phenomena is incorrect. Salt is certainly a physical phenomenon: salt (the physical reality, not the idea) exists without humans perceiving it. However, magenta is the human perception after visual reception and after the brain's interpretation of those neural signals of two different light waves with wavelengths at opposite ends of the light spectrum. If another organism had a brain which perceived the same combination of wavelengths as a different "color", which perception of "physical reality" would be correct? Is color to be defined as discrete physical measurements involving wavelength such as H-alpha or is color to be defined as the perception of light by a human brain which is common to 99.9% of humans (minus the brains or eyes which are incapable of processing or receiving color)? Is color a majority rule or objective reality?

Does the sensation of Deja Vu, which has been described as a neurophysiological phenomenon caused by the brain's misperception of physical reality, imply that the event experienced in Deja Vu actually happened before in physical reality? Certainly not. The perception is real, but it is not truly indicative of physical reality.

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Originally posted by MathRockBrock:Somehow our brains evolved such that, rather than being confused by a superposition of red and blue waves, we perceive all the permutations as shades of violets and magentas. But those superpositions exist regardless of what we call it.

I am not familiar with the minutiae of physics as I am not a physicist by trade. Can you explain how two different waves of light, one wave of one wavelength with another of a different wavelength, creates a new superimposed wave which has distinct physical characteristics responsible for imbuing physical reality with a color but which has characteristics which can not be described by physical science? What are the characteristics of this new wave? What is the wavelength? If you want magenta, what wavelength does a single light-source need to generate?

I do not think that the superposition of waves is responsible for the brain's perception of magenta, but rather the combination of neural impulses resulting from specific pigments in the cones reacting to distinct ranges of wavelengths of incoming waves of light.

I think, per the Sapir-Whorf hypothesis, if magenta is in your vocabulary then magenta is a color.

Russian speakers know both "goluboy" and "siniy" while English speakers just have "blue." But that doesn't make goluboy or siniy any less real than blue. See http://dx.doi.org/10.1073/pnas.0701644104 for more detail.

Is that in the same way as black isn't a colour, or in a whole new totally stupid way invented by people who have nothing better to do?

black isn't a colour, you see, it's a *shade*. A shade of what no-one has ever managed to explain. Nor have I ever known anyone to go to a shop and buy some shade jeans or use shade paint. Nor have I ever heard of someone refer to outer space as 'mostly shade', or a powercut as a shadeout.

oh, and as a colourblind person I hereby declare that orange doesn't exist, cos I'm physically incapable of seeing it.

Magenta, as it were, lies along what's commonly called the "pink-purple line" that runs across the bottom. All colors along this line do not exist as single wavelengths. But, all points inside the "color bag" above that line do not exist as single wavelengths, either

I'm confused, are you saying that no color exists as a single wavelength?

Correct me if I'm wrong, there are two ways that our brain can perceive the color green. Either an object emits or reflects light at the percise wavelength of green; or an object emits or reflects light at wavelengths of blue and yellow, which looks green to our eyes (how a TV works).

If: • red (from the H-alpha) has a discrete wavelength (656.281 nanometers), and • discrete wavelength exists in nature apart from human interpretation, butIf:• magenta has no discrete wavelength, and • discrete wavelength is necessary for something to exist in nature apart from human interpretation,Then:• Can magenta exist in nature? • Can magenta exist without human perception?• Does H-alpha red exist despite human perception? • Does H-alpha red exist in nature without human perception?• Is human perception necessary for something to exist?• Does the lack of human perception of something preclude something from existing?

Does existence precede essence, or does essence precede existence?

Hey look a philosotroll. This argument is pathetic.

Colors have independent existence because they are simply mixtures of wavelengths at different intensities. Our names for them and common perception of what color corresponds to what name may be governed by social conventions but the mixture of waves exists whether we want them to or not.

You know, even if we all chipped in and got you half a brain, you would still only have half a brain.

When I worked in manufacturing we worked with colored parts and it was critical that the parts met color specs. Everyone was given an extensive color test. It involved rows of pegs that the tester would mix on the table. I had put them in order from red to orange or orange to yellow, yellow to green, etc. We started with red to orange and I thought the test was pretty basic and kind of a waste of time. The differences were obvious. Then we got to green to blue and most of the pegs looked the same to me. I actually was so shocked at the sudden difficulty in telling them apart I asked if they really were all different shades. I was feeling a little down about it until I talked to the tester. It turns out that most people are a little color blind. The tester said she had only tested one person with a perfect score. She said my score was actually a little better then average. From then on I asked for help when checking the color match of blue and green parts.